As the Jerry Sandusky trial opens this week, many Americans seem to be asking the same question: when will it be over and when can this awful man’s long prison sentence start? This, of course, skips an important step – the trial itself. It may look like the prosecution has an open-and-shut case against Sandusky. But whatever the public is expecting, it is hardly a sure thing that the trial will end in a conviction.

Sandusky, a former Penn State assistant football coach, is facing 52 counts of child sex abuse. He is charged with abusing 10 boys over 15 years, using a charity he founded, Second Mile, to meet his victims. The pattern he is accused of is a classic one in crimes of this sort: targeting children, “grooming” them with friendship and gifts, and then molesting them.

Since the news of Sandusky’s indictment broke last fall, there has been no shortage of horrific stories and they have gotten big media play. One of the most disturbing came from Mike McQueary, a graduate assistant, who said that in 2001 he walked in on Sandusky showering with a boy who appeared to be about ten years old and engaging in what he was convinced was some kind of sexual activity. McQueary said he told Joe Paterno, Penn State’s legendary head coach, and other school officials but no one contacted law enforcement. Paterno died of lung cancer this past January.

Sandusky added to his troubles with his own words, offered up in some poorly considered interviews. Talking with NBC’s Bob Costas, Sandusky said, among other things, “I shouldn’t have showered with those kids.”

Prosecutors have one more important thing on their side: the number of alleged victims. The case is not a “He said, he said”—there are multiple accusers making similar accusations. But one problem they may have is that their case relies heavily on the testimony of those accusers, and lacks forensic evidence to back it up. The victims were young when the alleged events transpired, and quite a few years have gone by. McQueary was older, but the defense will likely try to undermine his testimony by pointing to some inconsistencies in how he has told his story.

Another likely defense tactic: suggesting that the accusers are trying to cash in. Within weeks of Sandusky’s indictment, one of his alleged victims had filed a civil lawsuit against Sandusky, Second Mile, and Penn State. Defense lawyers will also be looking for any weaknesses in the accusers, from psychological troubles to brushes with the law. Victims’ rights advocates complain that abuse victims get put on trial, but when people make sexual abuse charges, their memory and motives are going to be heavily scrutinized.

If the prosecution’s storyline is of a sexual predator preying on young boys, the defense will try to present Sandusky as a man who genuinely cares about young people and tried to do nice things for them. There have been reports that the prosecution will introduce handwritten letters from Sandusky to one of his accusers, which have been described as “love letters.” The defense would likely argue that the letters show a friendship, not an abusive relationship.

There have been plenty of cases over the years in which many people thought they “knew” someone was guilty – but the jury still acquitted. That was true for O.J. Simpson and, more recently, Casey Anthony – who was convicted of minor offenses but cleared of charges that she killed her two-year-old daughter. Prosecutors have to prove their case beyond a reasonable doubt, and in cases that rely heavily on testimony from witnesses who may have flaws or agendas, it is often easy for the defense to plant a seed of doubt in jurors’ minds.

That was what happened in last month’s trial of John Edwards. The jury acquitted the onetime presidential candidate on one count of campaign-finance violations and deadlocked on the rest. Two jurors who spoke afterwards said they believed Edwards was guilty, but they just did not think the prosecution presented enough evidence. One juror added that questions about the credibility of the prosecution’s star witness had also made it hard to convict.

Last Friday, the Sandusky prosecution scored an important victory when the judge denied a defense motion to dismiss the charges. Prosecutors may present a powerful case, and their case may go off without a hitch, but it is also possible that the defense will succeed in its mission: sowing doubt. As anyone who followed the Casey Anthony case can attest, there is no way of knowing how this case will turn out until there is a verdict.